I think you make a very fair point.
The vague warning might have been coz the MC doesn't want to reveal to Maya that he pays for sex. Also weird how the MC just kinda never tells Sage that Quinn is fucking with the HoT's reputation behind her back. About MC not telling Maya about Josy, I think it's out of shame, he doesn't really want to talk about one to the other, because he feels guilty about the whole situation, so he tells the minimum information possible, and that backfired epically. In College, I knew people from my class by name and last name, but the people I met on the corridor, I only knew their name and maybe nickname. It's not uncommon to meet people and know them on a first name only basis, but it does get weird when you're dicking or almost dicking them and don't know their last name.
As I said you make a fair point, those are definite Plot Contrivances that added together make a Plot Hole, but since it's not something integral to progression and understanding of the narrative, I find it to be very minor.